Image processing apparatus and method thereof

ABSTRACT

This invention provides a sample print which allows the user to easily set color adjustment parameters. To this end, upon outputting images which undergo color processing using a plurality of different parameter sets, a sample print mode of parallelly outputting a reference image and images which have different parameter sets of the image processing from the reference image, and are arranged around the reference image, and a sample print mode of parallelly outputting the reference image which is arranged at a corner of an image group including images in a specific hue direction, and images which have different parameter sets of the color processing from the reference image and are arranged between the corner and other corners, are prepared.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image processing apparatus andmethod thereof and, more particularly, to settings of color processingparameters.

2. Description of the Related Art

In recent years, the prevalence of digital cameras has facilitateddigitization of photos. As a result, the frequency of handling photoimage data on personal computers is on the rise. Furthermore, theprevalence of ink-jet printers now allows easy photo printing from photoimage data. Moreover, the prevalence of application software used tocorrect and modify images allows to freely execute image processing onpersonal computers. For example, color adjustment is made by adding cyanas a complementary color to a reddish image, or correction is applied tothe brightness of an image including a dark object image due tobacklight to increase the brightness of the object image.

In monochrome printing, the tone is very important for the finish of aprint. In monochrome printing, a warm black tone of an entirelyyellowish image, a cold black tone of an entirely bluish image, and thelike are generally known. That is, the tone to which the gray balance isbiased largely changes the impression of a print image. For this reason,a system which can easily adjust the gray balance to the tone that theuser wants is demanded.

In recent years, the color reproductivity of printers has improved toallow color adjustment with high precision. The user sets parametersrequired to perform color adjustment (color adjustment parameters) andcan finish a print image to have a desired tone. However, it is verydifficult to simultaneously set a plurality of color adjustmentparameters.

As a method of setting a desired tone, a plurality of color adjustmentparameters are set in a plurality of levels, and color processing isapplied to a source image (original image) using combinations of coloradjustment parameters of respective levels. A plurality of imagesprocessed based on different combinations of color adjustment parametersare laid out on one page and are printed. The user observes respectiveimages (index images) of a sample print, and selects an index image witha desired tone, thus setting the color adjustment parameters.

Upon printing an image without color adjustment, a print image withcolor reproduction unique to a printer is obtained. The colorreproductivity largely varies depending on printer models, and alsovaries depending on environmental conditions (temperature, humidity, andthe like) and the degree of wear of a printhead. Furthermore, the colorreproductivity largely varies depending on the combinations of printpaper types and color materials (inks or toners). In other words, inorder to realize the color reproductivity that the user wants, coloradjustment according to the printer models, environments, print papertypes, and color materials is indispensable.

FIG. 1 shows an example of a user interface (UI) of application softwareor a printer driver, which has a function of setting a plurality ofcolor adjustment parameters. With this function, the user can adjust thetone of an image to obtain a print image with a desired tone accordingto the printer models, environments, print paper types, and colormaterials. The UI shown in FIG. 1 has a slider bar used to adjust colorin the direction of red or cyan, a slider bar used to adjust color inthe direction of green or magenta, and a slider bar used to adjust colorin the direction of blue or yellow.

The user adjusts the tone of a print image by operating the slidersshown in FIG. 1. The user then instructs the application software orprinter driver to output a sample print as a target for the toneadjustment result. The application software or printer driver outputs asample print to have an image to which the color adjustment parametersdesignated by the operations of the slider bars are applied as areference image. Therefore, index images which are processed based onthe specific combinations of the color adjustment parameters set in aplurality of levels to have the current color adjustment parameters asthe center are arranged around the reference image.

The user observes the sample print to select an index image with adesired tone, and sets the color adjustment parameters by, e.g.,inputting the number of the index image of interest to the UI. Whenthere is no index image with the tone that the user desires, the coloradjustment parameters that the user desires fall outside the range ofthe combinations of the color adjustment parameters used to output thesample print. In this case, the user selects an index image which has atone approximate to the desired tone, and sets the color adjustmentparameters by, e.g., inputting the number of that index image. Afterthat, the user instructs to output a sample print again. As a result,the image to which the set color adjustment parameters are applied isused as a reference image, and a sample print including index imagesobtained by changing the color adjustment parameters to have that imageas the center can be output.

Japanese Patent Laid-Open No. 2002-027222 discloses a technique whichdetermines the color adjustment direction on a chromaticity coordinateplane after a primary sample print, and then outputs a secondary sampleprint based on a fine adjustment level count. That is, the primarysample print uses a two-dimensional layout based on chromaticitycoordinate parameters a* and b*. The secondary sample print after thedesignation of the color adjustment direction (hue value) uses atwo-dimensional layout based on lightness L* and saturation S asparameters. However, since this method uses the layout based on thelightness and saturation to obtain the secondary sample print, the huevalue must be accurately set in the stage of the primary sample print.In other words, the secondary sample print cannot print index imagesobtained by finely adjusting the hue value. For this reason, the usersearches index images with the fixed hue values for one with a desiredtone.

Japanese Patent No. 2773188 discloses sample printing (mosaic monitormode) in a digital color copying machine. This technique performs sampleprinting by calculating color adjustment parameters of a plurality oflevels upon applying predetermined arithmetic operations to referencevalues. Then, this technique performs sample printing again by settingthe color adjustment parameters of the index image selected by the useras reference values for the next color adjustment arithmetic operations.However, Japanese Patent No. 2773188 does not describe sample printingthat considers so that the user can easily recognize the hue andsaturation values, and cannot easily set the color adjustment parametersin association with the hue and saturation values.

With this technique, when the user selects an index image correspondingto the maximum values of the color adjustment parameters, these maximumvalues of the color adjustment parameters are set as reference values.In this case, the arrangement of index images on a sample print to beprinted again may not be easy for the user to see, and a measure againstsuch selection is not disclosed.

SUMMARY OF THE INVENTION

The first aspect of the present invention discloses an image processingapparatus comprising: an input section, arranged to input a referenceparameter set of color processing; a setting section, arranged to set aplurality of varied parameter sets obtained by changing parameters ofthe reference parameter set by a predetermined method to have theparameters as the center; and an image processor, arranged to lay out,on one page, a reference image generated by applying the colorprocessing using the reference parameter set to an image, and aplurality of index images generated by applying the color processingusing the plurality of varied parameter sets to the image, so as tooutput image data of the layout image to an image output device, whereinthe layout includes a first layout on which the reference image isarranged at nearly the center of the page, and the plurality of indeximages are arranged around the reference image in accordance with thevaried parameters, and a second layout on which the reference image isarranged at a corner of the page, and the plurality of index images arearranged between the corner and other corners of the page in accordancewith the varied parameters, and the first layout and the second layoutare selectively used.

The second aspect of the present invention discloses an image processingmethod of outputting images which undergo color processing using aplurality of different parameter sets, the method comprising the stepsof: parallelly outputting a reference image and images which havedifferent parameter sets of the image processing from the referenceimage, and are arranged around the reference image; and parallellyoutputting the reference image which is arranged at a corner of an imagegroup including images in a specific hue direction, and images whichhave different parameter sets of the color processing from the referenceimage and are arranged between the corner and other corners, wherein astep width of the parameter sets between neighboring images in thesecond outputting step is smaller than a step width between neighboringimages in the first outputting step.

According to the present invention, color processing parametersassociated with hue and saturation can be easily set.

The third aspect of the present invention discloses an image processingmethod of outputting images which undergo color processing using aplurality of different parameter sets, the method comprising the stepsof: parallelly outputting a reference image and images which havedifferent parameter sets of the image processing from the referenceimage, and are arranged around the reference image; and parallellyoutputting the reference image which is arranged at a corner of an imagegroup including images in a specific hue direction, and images whichhave different parameter sets of the color processing from the referenceimage and are arranged between the corner and other corners,

wherein a step width of the parameter sets between neighboring images inthe second outputting step is smaller than a step width betweenneighboring images in the first outputting step, wherein when a firstparameter included in the parameter set exceeds a predetermined range,the first parameter is limited to fall within the predetermined range,and a second parameter which is included in the parameter set and isdifferent from the first parameter is adjusted.

In consideration of a case wherein the color processing parameters falloutside a settable range, the color processing parameters can be set.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example of a user interface;

FIG. 2 is a block diagram showing the arrangement of an image processingapparatus according to an embodiment of the present invention;

FIG. 3 is a functional block diagram of the image processing apparatus;

FIG. 4 shows a state wherein respective color components of RGB signalsare independently set by color adjustment parameters;

FIG. 5 is a view for explaining the format of a sample print of thefirst type;

FIG. 6 is a view showing the color adjustment parameter values of areference image and some index images;

FIG. 7 is a view for explaining the format of a sample print of thesecond type;

FIG. 8 shows the hierarchical structure of menus provided by a GUI;

FIGS. 9 to 12 are views for explaining examples of distributions of thecolor adjustment parameters upon sample printing;

FIG. 13 is a view for explaining the distance from the reference imageto an outermost index image;

FIG. 14 is a flowchart for explaining distribution processing; and

FIG. 15 is a flowchart for explaining the method of setting coloradjustment parameters to have a uniform color difference ΔE.

DESCRIPTION OF THE EMBODIMENTS

Image processing according to preferred embodiments of the presentinvention will be described in detail hereinafter with reference to theaccompanying drawings.

First Embodiment

[Arrangement of Image Proccessing Apparatus]

FIG. 2 is a block diagram showing the arrangement of an image processingapparatus 100 according to this embodiment.

A CPU 108 implements image processing to be described later and controlsrespective components via a system bus 101 by executing programs storedin a ROM 110 and a hard disk drive (HDD) 107 using a RAM 109 as a workmemory.

The CPU 108 displays a graphical user interface (GUI), which is used todesignate execution of various kinds of processing and control anddisplay the execution status and execution result on a monitor 111 via avideo card 102. The user inputs instructions to the CPU 108 via the GUIby operating a keyboard 104 and mouse 105.

An interface (I/F) 103 is that for a serial bus such as USB (UniversalSerial Bus), IEEE1394, and the like. The I/F 103 receives a user inputfrom the keyboard 104 or mouse 105 via a serial bus 120 and transmits itto the CPU 108. To the serial bus 120, a digital camera 112 and printer113 can be connected. Therefore, the CPU 108 can input and output imagedata by communicating with the digital camera 112 via the I/F 103 andserial bus 120. Also, the CPU 108 can transmit image data to be printedto the printer 113 by communicating with it via the I/F 103 and serialbus 120.

Note that the image processing apparatus 100 can be implemented bysupplying various programs including an operating system (OS) and driversoftware to a general-purpose personal computer and making the computerexecute the programs.

FIG. 3 is a functional block diagram of the image processing apparatus100, and shows functions provided when the CPU 108 executes programsincluding the OS and various kinds of drivers, which are stored in theROM 110 and HDD 107.

Under the control of an OS 122, the CPU 108 can execute various kinds ofapplication software (AP) 121. A video card driver 124 is software usedwhen the OS 122 controls the video card 102, generates display data, andsupplies it to the video card 102. A printer driver 123 is a softwareused when the OS 122 communicates with the printer 113, generates printdata, and transmits it to the printer 113. A camera driver 125 issoftware used when the OS 122 communicates with the digital camera 112and exchanges image data.

[Operation of Image Processing Apparatus]

The application software 121 includes various kinds of software such asimage processing, a wordprocessor, a spreadsheet, a Web browser, and thelike. The OS 122 supplies various rendering commands (a text renderingcommand, graphics rendering command, image rendering command, and thelike) issued by the application software 121 to the video card driver124 and printer driver 123 to generate display data and print data.

The image processing software displays an image on the monitor 111, andedits and modifies text data such as characters and the like, graphicsdata such as figures and the like, and image data such as photo imagesand the like in accordance with user's instructions. The imageprocessing software requests the OS 122 to print the edited and modifiedimage data in accordance with a user's instruction. In this case, theimage processing software issues to the OS 122 a rendering command groupincluding a text rendering command for text data, a graphics renderingcommand for graphics data, and an image rendering command for imagedata.

Upon reception of a print request, the OS 122 supplies the renderingcommand group to the printer driver 123. Upon reception of the printrequest, the printer driver 123 receives and processes the renderingcommand group to generate print data which can be printed by the printer113, and transmits the print data to the printer 113.

The printer driver 123 sequentially applies image correction and rendersthe received rendering commands, and stores the rendered commands in anRGB 24-bit page memory assured on, e.g., the RAM 109. Upon completion ofrendering of the rendering commands, the printer driver 123 converts theimage data on the page memory into a data format that can be printed bythe printer 113, e.g., CMYK data, and transmits the CMYK data to theprinter 113. Note that the printer driver 123 may execute printing inband units obtained by dividing a page into bands having a predeterminedwidth in place of printing in page units using the page memory.

[Color Adjustment]

Image data sensed by the digital camera 112 is normally recorded andstored in an SRAM of a memory card. The user can fetch the image dataonto the HDD 107 of the image processing apparatus 100 via the cameradriver 125 of the image processing apparatus 100. Of course, the usermay connect a card reader to the serial bus 120, and may directly readout the image data from the memory card. The user then launches theimage processing software, and adjusts the color balance of the imagedata fetched onto the HDD 107. Also, the user can execute similar imageprocessing using the printer driver 123.

Note that the image data of the digital camera 112 is normally recordedand stored as YCbCr signals in the JPEG format. On the other hand, theimage processing apparatus 100 handles image data as RGB signals.Therefore, the JPEG image data fetched from the digital camera 112 istemporarily converted into bitmap image data of RGB signals before imageprocessing.

An example in which a red-cyan value (RC value), green-magenta value (GMvalue), and blue-yellow value (BY value) are used as color adjustmentparameters (color processing parameters) will be described hereinafter.The application software 121 or printer driver 123 allows the user toadjust the color adjustment parameters via the GUI that displays theslider bars, as shown in FIG. 1. The user can also directly input thevalues of the color adjustment parameters by inputting numerical valuesusing the keyboard 104.

FIG. 4 shows a state wherein the respective color components of RGBsignals are independently processed by respective color adjustmentparameters. That is, as shown in FIG. 4, of RGB signals of a referenceimage, an R signal is processed by an RC value, a G signal is processedby a GM value, and a B signal is processed by a BY value, thusconsequently obtaining R′G′B′ signals. The arithmetic operation methodof the R′G′B′ signals is not particularly limited. For example, in caseof an R signal=150 (8 bits) and an RC value=30, the following arithmeticoperations may be made.R′=R+RC=150+30=180orR′=R×(1+RC/Range)=150×1.3=195Alternatively, using the RC value as a gamma value,R′=R/255^((1+RC/Range))×255=150 255^(1/1.3)×255=169where when 0≦R′or R′≧255, the signal value is clipped to R′=0 or R′=255,and

Range is the absolute value of the range of the color adjustmentparameter (for example, 100 if the color adjustment parameter rangesfrom −50 to +50).

When the user applies the above color adjustment to an image to beprinted, he or she adjusts respective color adjustment parameters whileobserving the tone of the printed image. However, it is difficult for anormal user to appropriately set a plurality of color adjustmentparameters at one time unless he or she were an expert user. Hence, theuser makes the aforementioned sample print, and then sets coloradjustment parameters. That is, the plurality of color adjustmentparameters are set in a plurality of levels, and the user selects anindex image with a desired tone from those based on differentcombinations of the color adjustment parameters of respective levels,thus setting the color adjustment parameters.

Note that the GUI shown in FIG. 1 has a combination of the RC value, GMvalue, and BY value as color adjustment parameters. However, the coloradjustment parameters are not limited to them. For example, brightnessand contrast levels, strong and weak levels of correction such asbacklight correction, and the like are defined as individual coloradjustment parameters, and the GUI allows the user to adjust at leasttwo of these color adjustment parameters as a combination and to printimages that have undergone color adjustment in a plurality of levelsusing different combinations of these parameters as a sample.

[Layout of Sample Print]

Assume that the first embodiment comprises the following two types ofsample prints since there are three color adjustment parameters, i.e.,the RC value, GM value, and BY value. Note that the output destinationof a sample print is not limited to the printer 113. For example, asample print may be output to an image output device such as the monitor111 or the like so as to display a preview image.

FIG. 5 is a view for explaining the format of a sample print of thefirst type, and shows a state wherein index images are printed on oneface of a print medium. As shown in FIG. 5, a reference image isarranged at nearly the center of a page, and index images are laid outin a hexagonal pattern having six hues, i.e., yellow (Y), red (R),magenta (M), blue (B), cyan (C), and green (G), as vertices. Theabsolute value of each color adjustment parameter increases from thereference image at nearly the center toward each vertex. Note that asymbol (e.g., Y1, CB1, or the like) assigned to each index image is anindex number. In the following description, for example, an index imagewith symbol Xn will be referred to as “index image Xn”.

FIG. 6 shows the color adjustment parameter values of the referenceimage and some index images. The reference image has a BY value=“0”, butindex image Y3 which advances by one level from the reference imagetoward the Y vertex has a BY value=“−10”. Upon advancing one more level,index image Y2 has a BY value=“−20”, and index image Y1 at the Y vertexhas a BY value=“−30”. In this way, the BY value decreases from thereference image toward the Y vertex. Conversely, upon advancing from thereference image toward the B vertex, the BY values of index imagesincrease like “10”, “20”, and “30”.

Note that the step value of the BY value is “10” in the example of FIG.6, but it can be arbitrarily set. The step width of each coloradjustment parameter may be predetermined or may be varied for eachsample print in accordance with the tone of a reference image.

In the following description, the sample print with the hexagonal layoutshown in FIG. 5 will be referred to as an “all-hue sample print”. Theall-hue sample print is used to determine a hue direction to executecolor adjustment with respect to the reference image. In other words,the all-hue sample print is preferably used when the user wants toexecute color adjustment associated with hue rather than that associatedwith saturation, or wants to know a change in tone upon changing huewith respect to the set color adjustment parameters.

FIG. 7 is a view for explaining the format of a sample print of thesecond type and shows a state wherein index images are printed on oneface of a print medium. As shown in FIG. 7, a reference image isarranged at one corner of the page, and index images are laid out in arectangular pattern having three hues (Y, R, and M in FIG. 7) asvertices. Note that the numbers of images arranged in the vertical andhorizontal directions are equal to each other.

For example, when the user selects a red hue from the six hues, thereference image is arranged at the lower left corner, the R vertex isarranged at the upper right corner diagonal with respect to thereference image, and M and Y which neighbor R are arranged at the tworemaining vertices. Like in the all-hue sample print, the absolute valueof each color adjustment parameter increases from the reference imagetoward each vertex. In the following description, the sample print withthe rectangular layout shown in FIG. 7 will be referred to as an“individual-hue sample print”, and the sample print after selection ofthe red hue, as shown in FIG. 7, will be referred to as a “red-huesample print”. The individual-hue sample print is used when the userroughly determines color adjustment associated with hue, and wants toapply color adjustment associated with saturation.

On the red-hue sample print, an image arranged at the upper right cornerhas a largest saturation value, and the saturation value decreases withincreasing distance from the image arranged at the upper right corner.

Note that upon printing, e.g., the red-hue sample print, the referenceimage, and index images bounded by those at the M, R, and Y vertices maybe extracted from the all-hue sample print, and may undergo sampleprinting. However, on the individual-hue sample print, it is preferableto set a smaller step width of each color adjustment parameter than onthe all-hue sample print and to express a tone change more finely. As aresult, the user can set a rough goal of color adjustment associatedwith hue by the all-hue sample print. Then, the user can observe a tonechange or saturation change in more detail using the individual-huesample print which has the hue (hue to be adjusted), which is given asthe rough goal, as an axis. The user can select an index imagecorresponding to appropriate color adjustment parameters from theindividual-hue sample print.

Note that the case has been exemplified wherein the red hue is selected.Also, the same applies to a case wherein another hue such as yellow,cyan, or the like is selected.

In this manner, when the user wants to examine a tone change associatedwith hue or to apply color adjustment associated with hue, he or sheuses the all-hue sample print. On the other hand, when the user wants toexamine a tone change associated with. saturation or to apply coloradjustment associated with saturation, he or she uses the individual-huesample print. Alternatively, the user roughly determines coloradjustment associated with hue to be applied to a reference image byobserving the all-hue sample print, and then explores the tone in detailby observing the individual-hue sample print to select an index image(to determine the color adjustment parameters).

FIG. 8 shows the hierarchical structure of menus provided by the GUI ofthe application software 121 or printer driver 123. Upon selecting“sample print” on a menu bar, a plurality of sub menus are displayed, asshown in FIG. 8. The user can arbitrarily select a sub menu “all-hueprint” corresponding to the all-hue sample print or one of sub menus“R-direction print” to. “M-direction print” corresponding to eachindividual-hue sample print, and can execute the selected sub menu. Notethat the user interface need not always adopt the pull-down menu form aslong as it makes the user select one of a plurality of choices. Forexample, the user may check the all-hue sample print or one ofindividual-hue sample prints using a radio button to execute sampleprinting.

[Distribution of Color Adjustment Parameters]

The values of the color adjustment parameters of the reference image arechanged to set another combination of color adjustment parameters(varied color adjustment parameters). In this case, assume that the stepwidth between neighboring color adjustment parameter values is set inadvance to be “10”. If the BY value of the reference image is “0”, asshown in FIG. 6, that of index image Y3 is “−10”. Furthermore, the BYvalue of index image Y2 is “−20”, and that of index image Y1 at the Yvertex is “−30”. This step width remains the same even when thereference image has undergone color adjustment.

When the BY value of the reference image is set to be “−5”, that ofindex image Y3 is “−15”. Furthermore, the BY value of index image Y2 is“−25”, and that of index image Y1 at the vertex is “−35”.

If the absolute value of each color adjustment parameter set for thereference image is large, the value of the varied color adjustmentparameter may exceed the setting range in some index images. Forexample, if the BY value of the reference image is set to be “−30”, thatof index image Y1 is “−60”. However, if the setting range of the coloradjustment parameter value is from −50 to +50, as shown in FIG. 1, avalue whose absolute value exceeds “50” cannot be set.

Hence, when the varied color adjustment parameter value has exceeded thesetting range, it may be clipped to the upper limit value (e.g., +50) orlower limit value (e.g., −50). However, the BY values of both indeximages Y1 and Y2 become “−50”, and index images having the same BYvalues line up on one sample print. This is not preferable if thepurpose of sample printing is considered.

To solve this problem, the first embodiment processes as follows when atleast one of the three color adjustment parameters exceeds the settingrange. That is, the varied color adjustment parameter value whichexceeds the setting range is clipped to the upper or lower limit value,and other color adjustment parameter values are changed. In this manner,the sample print never includes index images having the same combinationof color adjustment parameters.

Note that the three color adjustment parameters are respectively calledfirst, second, and third parameters. If the first, second, and thirdparameters are different parameters, the first parameter may be any oneof the RC value, GM value, and BY value. Likewise, if the first, second,and third parameters are different parameters, the second and thirdparameters may be any one of the RC value, GM value, and BY value.

FIG. 9 is a view for explaining an example of distribution of the coloradjustment parameters upon sample printing. FIG. 14 is a flowchart forexplaining distribution processing, and the CPU 108 executes thisprocessing. Note that FIG. 14 shows processing for only one index image,but the CPU 108 repeats the processing shown in FIG. 14 for all theindex images.

For example, assume that the user sets the color adjustment parametervalues to have an RC value=0, GM value=0, and BY value=−40, andinstructs to print a sample print. In other words, the color adjustmentparameters of the reference image respectively have the RC value=0, GMvalue=0, and BY value=−40.

In this case, as shown in FIG. 9, the varied color adjustment parametervalues of index image Y3 are respectively set to have the RC value=0, GMvalue=0, and BY value=−50 (S100), all of which fall within the settingrange (S101).

The varied color adjustment parameters of index image Y2 are set to havethe RC value=0, GM value=0, and BY value=−60 (S100). In this case, theBY value is below the minimum value “−50” of the setting range (S101).Hence, the BY value of index image Y2 is clipped to “−50” (S102), andthe remaining value “−10” of the BY value after clipping is distributedto the RC value and GM value to set the RC value=5 and GM value=5(S103). Increases in RC value and GM value increase the ratios of the Rand G color components, and the image is emphasized in the direction ofthe Y-hue axis. Likewise, of the varied color adjustment parameters ofindex image Y1, the BY value is clipped to “−50” (S102), and theremaining value “−20” of the BY value after clipping is distributed tothe RC value and GM value to set the RC value=10 and GM value=10 (S103).

When the BY value has reached its lower limit value, index images Y1 andY2 cannot be emphasized (color-adjusted) in the direction of the Y-hueaxis by increasing the BY value. Hence, by increasing the RC value andGM value in correspondence with the remaining value of the BY valueafter clipping, index images Y1 and Y2 are emphasized (color-adjusted)in the direction of the Y-hue axis relative to index image Y3.

The same applies to other tones. For example, when the RC value exceeds“+50” of the setting range, the GM value and BY value decrease incorrespondence with the remaining value of the RC value clipped to “+50”to decrease the ratios of the G and B color components, thus emphasizing(color-adjusting) an image in the direction of the R-hue axis.

FIG. 10 is a view for explaining an example of distribution of variedcolor adjustment parameters upon sample printing, and shows the variedcolor adjustment parameters of respective index image when the BY valueexceeds the setting range, as in FIG. 9.

For example, the RC value increases in increments of the step width byfixing the GM value and BY value along the R-hue axis (referenceimage→index image R3→index image R2→index image R1). Likewise, the GMvalue increases in increments of the step width by fixing the RC valueand BY value along the G-hue axis (reference image to index imageG3→index image G2→index image G1). Similarly, the BY value of indeximages on the B-hue axis increases in increments of the step width fromthe reference image (center) toward the outermost image, and the GMvalue and RC value of index images on the M- and C-hue axes decrease indecrements of the step width from the reference image (center) towardthe outermost images.

Index images sandwiched between neighboring hue axes are set withintermediate varied parameter values of those of index images on therespective hue axes, as shown in FIG. 10. The RC value of index imageRY1 is set to “20” by subtracting the step width from that of indeximage R1, and the BY value is set to “−50” by subtracting the step widthfrom that of index image R1. Likewise, by subtracting the step widthfrom the RC value and BY value of index image RY2, the RC value=10 andBY value=−60, and the BY value drops below the setting range in thiscase. Like in index images Y1 and Y2, the BY value of index image RY2 isclipped to “−50”, and the remaining value after clipping is added to theRC value and GM value to obtain the RC value=15 and GM value=5. The stepwidth is subtracted from the RC value of index image RY3 with respect toindex image R3 to obtain “10”, and is also subtracted from the BY valueto obtain “−50”. The same applies to index images YGn, BMn, and CBn(n=1, 2, 3).

Upon clipping the varied color adjustment parameters when the values ofthe varied color adjustment parameters exceed the settable range on thesample print, a plurality of index images with the same tone exist, thusimpairing the functions of the sample print. When the varied coloradjustment parameters are clipped, as described above, the plurality ofcolor adjustment parameters are adjusted in conjunction with each otherto prevent the above bad effect, and the sample print with good visualtone balance can be provided. Note that the adjustment that interlocksthe plurality of color adjustment parameters can be applied to theindividual-hue sample print shown in FIG. 7.

The individual-hue sample print has a format obtained by extracting someindex images from the all-hue sample print. Therefore, as describedabove, it is preferable to set the smaller step width of the coloradjustment parameters of the individual-hue sample print than theall-hue sample print and to express the tone change more finely. Forexample, the number of index images that can be printed on theindividual-hue sample print is approximately four times that of theall-hue sample print. Therefore, upon reception of an all-hue sampleprint instruction, the color adjustment parameters may be changed bysetting the step width=10, and upon reception of an individual-huesample print instruction, the color adjustment parameters may be set bysetting the step width=2 to 3.

[Brightness Adjustment]

Upon adjusting only one color adjustment parameter, only a color signalcorresponding to that color adjustment parameter of RGB signals isprocessed. For example, when only the setting of the RC value ischanged, only the processing for the R signal is changed, and those forthe G and B signals remain unchanged. As a result, not only the tone butalso the brightness of an image are changed. To prevent this problem,when, for example, the RC value is increased, the GM value and BY valuesare decreased in accordance with the increment of the R signal so that aluminance value Y=0.3R+0.6G+0.1B remains unchanged. In this way, evenwhen the reference image has undergone color adjustment, the brightnessvalues of all index images on the sample print can be maintained.

[Holding Method of Color Adjustment Parameters]

The absolute values of the color adjustment parameters may be held forrespective index images including the reference image in an area assuredon a memory such as the RAM 109 or the like. As another holding method,the color adjustment parameters of the reference image may be held, andthe varied color adjustment parameters of other index images may be heldas relative values (differences) to the color adjustment parameters ofthe reference image.

FIG. 11 is a view for explaining an example of distribution of the coloradjustment parameters upon sample printing, and shows the differences ofthe varied color adjustment parameters (to be simply referred to asdifferences hereinafter) of index images on the Y-hue axis. All thedifferences, i.e., the ΔRC, ΔGM, and ΔBY values of the reference imageare obviously=“0”. The differences of index image Y3 are set to have theΔRC value=5, ΔGM value=5, and ΔBY value=−10, and those of index image Y2are set to have the ΔRC value=10, ΔGM value=10, and ΔBY value=−20.

Actual varied color adjustment parameters have values obtained by addingthe differences to the values of the color adjustment parameters of thereference image. For example, assuming that the color adjustmentparameters of the reference image are respectively the RC value=−30, GMvalue=−30, and BY value=−30, the color adjustment parameters of thereference image and index images shown in FIG. 11 are as shown in FIG.12. That is, the varied color adjustment parameters of index image Y3are the RC value=−30+5=−25, GM value=−30+5=−25, and BY value=−30−10=−40.Also, the varied color adjustment parameters of index image Y3 are theRC value=−30+10=−20, GM value=−30+10=−20, and BY value=−30−20=−50.

In this case as well, the values of the varied color adjustmentparameters may exceed the setting range. As shown in FIG. 12, the valuesof the varied color adjustment parameters of index images Y3 and Y2 fallwithin the settable range (−50 to +50). However, the BY value of indeximage Y1 is −30−30=−60, and exceeds the settable range. In the samemanner as in the above description, as shown in FIG. 12, the BY value ofindex image Y1 which exceeds the settable range is clipped to “−50”, andthe remaining value “−10” after clipping is distributed to other coloradjustment parameters. As a result, the varied color adjustmentparameters of index image Y1 are the RC value=−30+15+5=−10, GMvalue=−30+15+5=−10, and BY value=−50.

The adjustment that interlocks the plurality of color adjustmentparameters can also be applied to the individual-hue sample print shownin FIG. 7.

[Distribution of Color Adjustment Parameters in Consideration of ColorDifference]

In the above example of the sample print, the color adjustment parametervalues are changed by the unique step width (e.g., 10) from thereference image (center) toward outermost images. However, a method ofchanging the color adjustment parameters so that neighboring indeximages have a uniform color difference ΔE on the chromaticity coordinatesystem may be used.

For example, on the all-hue sample print shown in FIG. 5, neighboringindex images have a predetermined color difference in each hue axisdirection. As a result, since the color difference ΔE uniformly changesin accordance with the distance between neighboring index images, theuser can observe as if the tones of index images change smoothly due tothe human visual sense.

A method of calculating the color adjustment parameters to have auniform color difference ΔE between neighboring index images in a casewherein an sRGB space is assumed on the hexagonal layout shown in FIG. 5will be described below.

FIG. 15 is a flowchart for explaining the method of setting the coloradjustment parameters to have a uniform color difference ΔE, and the CPU108 executes this processing.

The CPU 108 determines a color difference ΔE between neighboring indeximages (S201). For example, the CPU 108 may set a color difference ΔE=3between neighboring index images. The setting value of the colordifference ΔE is variable, but it is set to be equal to or larger than avalue that allows the human visual sense to identify the colordifference.

The CPU 108 sets index images (RGB values) separated from the referenceimage by ΔE×n (n is a natural number) as many as required (S202). TheCPU 108 then calculates the distance between the reference image and anarbitrary index image as a*b* values (√(a*² +b*²)) on the chromaticitycoordinate system (S203)

For example, the CPU 108 converts the central pint (R, G, B)=(128, 128,128) of the color space into Lab values on the sRGB color space, andadds the previously calculated distance a*b* values of the arbitraryindex image to them (S204). The CPU 108 then converts the sums into RGBsignal values (R′G′B′ values) (S205).

The CPU 108 calculates an RC value that converts R into R′, a GM valuethat converts G into G′, and a BY value that converts B into B′, andsets them as varied color adjustment parameters of the index image ofinterest (S206). The CPU 108 adjusts the reference image using the setvaried color adjustment parameters, and arranges the image as thearrangement result at an appropriate position as the index image ofinterest.

Note that the CPU 108 calculates the RC values, SM values, and BY valueswhich convert RGB values into R′S′B′ values in advance for all thepossible ranges of the color adjustment parameters. When the calculationresults are held as a table of the application software 121 or printerdriver 123, the color adjustment parameters can be calculated in a shortperiod of time. Of course, the above table may be prepared for, e.g.,the sRGB space and printer gamut in place of the possible ranges of thecolor adjustment parameters.

Note that the color space of a printer may be used in place of the sRGBspace. In this way, the tone of the sample print expresses the colordifference ΔE more faithfully. The representative point as the center ofthe color space is not limited to (R, G, B)=(128, 128, 128), and otherpoints may be used. In the description of the above example, the colordifference ΔE on the chromaticity coordinate system is used.Alternatively, RGB signals may be converted into YCbCr signals, and acolor difference ΔCbCr on the CbCr plane or a color difference ΔRGB onthe RGB space may be used.

[Modification]

The all-hue sample print is not limited to the hexagonal layout, but maybe varied in correspondence with the number of color adjustmentparameters. In the above description, since three color adjustmentparameters are used, a hexagon in which the reference image is arrangedat the center to have these color adjustment parameters as axes isselected. However, if the number of color adjustment parameters is two,a rectangle may be used, and if it is four, an octagon may be used. Thatis, if the number of color adjustment parameters is N, a 2N-gonal layoutwhich is twice the number of color adjustment parameters is preferablyused. The reference image may be arranged at the center of the layout(that of a polygon), and index images whose color adjustment parametersare changed toward respective vertices may be arranged.

The layout of each individual-hue sample print can also be changed. Inthe above description, since three color adjustment parameters are used,the hues (directions of the axes) are narrowed down to have theseparameters as axes, so a rectangle in which the reference image isarranged at a corner is selected. However, if the number of coloradjustment parameters is two, a triangle may be used.

In order to present the color adjustment parameters of index images, theRC value, GM value, and BY value are printed under each index image. Asa result, the user can search for an index image (or an image group)indicating a desired tone from index images, and can finely adjust thecolor adjustment parameters with reference to the color adjustmentparameter values printed under that (or those) index image (or images).

Furthermore, in the description of the above example, the applicationsoftware 121 or printer driver 123 sets the color adjustment parameters.However, some digital cameras 112 which perform direct print using theprinter 113 without the intervention of any personal computer are alsocommercially available. In this case, a GUI used to set color adjustmentparameters is displayed on the monitor of the digital camera 112 orprinter 113, and the user sets the color adjustment parameters andinputs a sample print instruction using that GUI.

In this way, two different layouts, i.e., a layout on which thereference image is arranged at the center, and a layout on which it isarranged at a corner are prepared as sample prints. When the user wantsto examine a tone change associated with hue or to apply coloradjustment in association with hue, he or she uses the layout on whichthe reference image is arranged at the center. When the user wants toexamine a tone change associated with saturation or to apply coloradjustment in association with saturation, he or she uses the layout onwhich the reference image is arranged at the corner. Hence, the user canselectively use the layouts according to the use purpose.

When the color adjustment parameter value of an arbitrary index imageexceeds the settable range on the sample print, a sample print withdifferent tones of all index images can be obtained by adjusting theplurality of color adjustment parameters in conjunction with each other.

Second Embodiment

Image processing according to the second embodiment of the presentinvention will be described below. Note that the same reference numeralsin the second embodiment denote the same parts as in the firstembodiment, and a detailed description thereof will be omitted.

The first embodiment has explained the method of changing the tones ofall index images on the sample print by adjusting a plurality of coloradjustment parameters in conjunction with each other when the coloradjustment parameter value exceeds the settable range on the sampleprint. The second embodiment will explain a method of avoiding the badeffect that the color adjustment parameter value exceeds the settablerange in accordance with the color space.

For example, the sRGB space or the printer color space (RGB space) isconverted into the chromaticity coordinate system. Then, as shown inFIG. 13, color differences ΔEx between the reference image and outermostindex images are calculated. Then, an index image with a minimum colordifference ΔEx is detected. In the example of FIG. 13, index image R1 isan outermost index image with the minimum color difference ΔEx. That is,the color difference ΔEx between the reference image and index image R1is calculated.

Next, the color difference ΔEx is equally divided by the number N−1 ofindex images (distance) on one side of the sample print. In the exampleshown in FIG. 13, since the number of index images on one side is four,the distance=3, and ΔEx/3 is to be calculated. Finally, in the methoddescribed in [distribution of color adjustment parameters inconsideration of color difference], the varied color adjustmentparameters of respective index images are set to have ΔE=ΔEx/(N−1).

In this way, by distributing the color adjustment parameters based on anindex image which has a minimum color difference from the referenceimage, the values of the varied color adjustment parameters never exceedthe settable range. However, in case of equal division, a lower limitmust be set for the color difference ΔE between neighboring indeximages. That is, when the color difference between the reference imageand outermost index image is small, when the number of index images onone side is large, and so forth, the color difference ΔE betweenneighboring index images may become very small.

Hence, a value that allows the human visual sense to identify the colordifference is set as a lower limit value of the color difference ΔE.When the color difference ΔE becomes less than the lower limit value, awarning message may be displayed on a GUI to re-set the color adjustmentparameters of the reference image, or the number of index images on oneside is reduced upon sample printing after the warning message may bedisplayed on the GUI.

Other Embodiment

The present invention can be applied to a system constituted by aplurality of devices (e.g., host computer, interface, reader, printer)or to an apparatus comprising a single device (e.g., copying machine,facsimile machine).

Further, the object of the present invention can also be achieved byproviding a storage medium storing program codes for performing theaforesaid processes to a computer system or apparatus (e.g., a personalcomputer), reading the program codes, by a CPU or MPU of the computersystem or apparatus, from the storage medium, then executing theprogram.

In this case, the program codes read from the storage medium realize thefunctions according to the embodiments, and the storage medium storingthe program codes constitutes the invention.

Further, the storage medium, such as a floppy disk, a hard disk, anoptical disk, a magneto-optical disk, CD-ROM, CD-R, a magnetic tape, anon-volatile type memory card, and ROM can be used for providing theprogram codes.

Furthermore, besides aforesaid functions according to the aboveembodiments are realized by executing the program codes which are readby a computer, the present invention includes a case where an OS(operating system) or the like working on the computer performs a partor entire processes in accordance with designations of the program codesand realizes functions according to the above embodiments.

Furthermore, the present invention also includes a case where, after theprogram codes read from the storage medium are written in a functionexpansion card which is inserted into the computer or in a memoryprovided in a function expansion unit which is connected to thecomputer, CPU or the like contained in the function expansion card orunit performs a part or entire process in accordance with designationsof the program codes and realizes functions of the above embodiments.

In a case where the present invention is applied to the aforesaidstorage medium, the storage medium stores program codes corresponding tothe flowcharts described in the embodiments.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2005-380173, filed Dec. 28, 2005, which is hereby incorporated byreference herein in its entirety.

1. An image processing apparatus comprising: an input section, arrangedto input a reference parameter set of color processing; a settingsection, arranged to set a plurality of varied parameter sets obtainedby changing parameters of the reference parameter set by a predeterminedmethod to have the parameters as the center; and an image processor,arranged to lay out, on one page, a reference image generated byapplying the color processing using the reference parameter set to animage, and a plurality of index images generated by applying the colorprocessing using the plurality of varied parameter sets to the image, soas to output image data of the layout image to an image output device,wherein the layout includes a first layout on which the reference imageis arranged at nearly the center of the page, and the plurality of indeximages are arranged around the reference image in accordance with thevaried parameters, and a second layout on which the reference image isarranged at a corner of the page, and the plurality of index images arearranged between the corner and other corners of the page in accordancewith the varied parameters, and the first layout and the second layoutare selectively used.
 2. The apparatus according to claim 1, whereinwhen one parameter of the varied parameter set falls outside a settablerange, said setting section clips that parameter to a maximum value or aminimum value of the settable range, and distributes a remaining valueafter clipping to other parameters of the varied parameter set.
 3. Theapparatus according to claim 1, wherein said setting section sets theplurality of varied parameter sets by changing one parameter of thereference parameter set by a predetermined step width.
 4. The apparatusaccording to claim 3, wherein the step width for the second layout issmaller than the step width for the first layout.
 5. The apparatusaccording to claim 1, wherein the first layout and the second layouthave axes as many as the number of parameters in the parameter set. 6.The apparatus according to claim 1, wherein said setting section setsthe plurality of varied parameter sets by changing parameters of thereference parameter set so that color differences between the referenceimage and index images which neighbor the reference image and colordifferences between the neighboring index images become approximatelyequal to each other.
 7. The apparatus according to claim 6, wherein saidsetting section sets the plurality of varied parameter sets using atable which holds arithmetic results of parameter sets havingapproximately equal color differences in association with the settablerange of the varied parameter set, an sRGB space, or a color gamut ofthe image output device.
 8. The apparatus according to claim 6, furthercomprising a resetting section, arranged to detect an index image whichis located at an outermost position of the layout and has a minimumcolor difference from the reference image, and to reset the variedparameter sets based on a quotient obtained by dividing the colordifference by a distance between that index image and the referenceimage.
 9. The apparatus according to claim 8, wherein when the quotientis not more than a threshold, said resetting section uses apredetermined value in place of the quotient.
 10. An image processingmethod comprising the steps of: inputting a reference parameter set ofcolor processing; setting a plurality of varied parameter sets obtainedby changing parameters of the reference parameter set by a predeterminedmethod to have the parameters as the center; and laying out, on onepage, a reference image generated by applying the color processing usingthe reference parameter set to an image, and a plurality of index imagesgenerated by applying the color processing using the plurality of variedparameter sets to the image, so as to output image data of the layoutimage to an image output device, wherein the layout includes a firstlayout on which the reference image is arranged at nearly the center ofthe page, and the plurality of index images are arranged around thereference image in accordance with the varied parameters, and a secondlayout on which the reference image is arranged at a corner of the page,and the plurality of index images are arranged between the corner andother corners of the page in accordance with the varied parameters, andthe first layout and the second layout are selectively used.
 11. Animage processing method of outputting images which undergo colorprocessing using a plurality of different parameter sets, the methodcomprising the steps of: parallelly outputting a reference image andimages which have different parameter sets of the image processing fromthe reference image, and are arranged around the reference image; andparallelly outputting the reference image which is arranged at a cornerof an image group including images in a specific hue direction, andimages which have different parameter sets of the color processing fromthe reference image and are arranged between the corner and othercorners, wherein a step width of the parameter sets between neighboringimages in the second outputting step is smaller than a step widthbetween neighboring images in the first outputting step.
 12. The methodaccording to claim 11, wherein when a first parameter included in theparameter set exceeds a predetermined range, the first parameter islimited to fall within the predetermined range, and a second parameterwhich is included in the parameter set and is different from the firstparameter is adjusted.
 13. An image processing apparatus for outputtingimages which undergo color processing using a plurality of differentparameter sets, comprising: a first output section, arranged toparallelly output a reference image and images which have differentparameter sets of the image processing from the reference image, and arearranged around the reference image; and a second output section,arranged to parallelly output the reference image which is arranged at acorner of an image group including images in a specific hue direction,and images which have different parameter sets of the color processingfrom the reference image and are arranged between the corner and othercorners, wherein a step width of the parameter sets between neighboringimages in said second output section is smaller than a step widthbetween neighboring images in said first output section.
 14. Theapparatus according to claim 13, further comprising a controller,arranged to limit, when a first parameter included in the parameter setexceeds a predetermined range, the first parameter to fall within thepredetermined range, and to adjust a second parameter which is includedin the parameter set and is different from the first parameter.
 15. Acomputer program product stored on a computer readable medium comprisingprogram code for an image processing method, the method comprising thesteps of: inputting a reference parameter set of color processing;setting a plurality of varied parameter sets obtained by changingparameters of the reference parameter set by a predetermined method tohave the parameters as the center; and laying out, on one page, areference image generated by applying the color processing using thereference parameter set to an image, and a plurality of index imagesgenerated by applying the color processing using the plurality of variedparameter sets to the image, so as to output image data of the layoutimage to an image output device, wherein the layout includes a firstlayout on which the reference image is arranged at nearly the center ofthe page, and the plurality of index images are arranged around thereference image in accordance with the varied parameters, and a secondlayout on which the reference image is arranged at a corner of the page,and the plurality of index images are arranged between the corner andother corners of the page in accordance with the varied parameters, andthe first layout and the second layout are selectively used.
 16. Acomputer program product stored on a computer readable medium comprisingprogram code for an image processing method of outputting images whichundergo color processing using a plurality of different parameter sets,the method comprising the steps of: parallelly outputting a referenceimage and images which have different parameter sets of the imageprocessing from the reference image, and are arranged around thereference image; and parallelly outputting the reference image which isarranged at a corner of an image group including images in a specifichue direction, and images which have different parameter sets of thecolor processing from the reference image and are arranged between thecorner and other corners, wherein a step width of the parameter setsbetween neighboring images in the second outputting step is smaller thana step width between neighboring images in the first outputting step.